Values Of Flow Rate Research Articles

Effects of Delayed-Onset Muscle Pain on Respiratory Muscle Function

Background: Delayed-onset muscle soreness (DOMS) has been widely examined in the peripheral muscles; however, studies showing the potential effects of DOMS on respiratory function are limited. Hypothesis: DOMS in trunk muscles has a negative effect on respiratory function parameters, respiratory muscle strength, respiratory muscle endurance, and exercise capacity. Study Design: Prospective cohort study. Level of Evidence: Level 2. Methods: In 24 healthy participants with a mean age of 21 ± 2 years, DOMS was induced for the trunk muscles with a load equal to 80% of the maximum repetitive voluntary contraction. Pulmonary function parameters, respiratory muscle strength and endurance, exercise capacity, pain, fatigue, and dyspnea perception severity were recorded before DOMS and at 24 and 48 hours after DOMS. Results: After DOMS, decreases were observed in respiratory function parameters, namely, forced vital capacity, forced expiratory volume in the first second, vital capacity, and 25% to 75% flow rate value of forced expiratory volume (25% to 75%) ( P = 0.02, P = 0.02, P < 0.01, P = 0.01, respectively). Maximal inspiratory pressure and exercise capacity also decreased ( P = 0.02, P < 0.01, respectively). No difference was observed between all 3 measurements of maximal expiratory pressure (MEP) and MEP% values ( P1 = P2 = P3 ≥ 0.99). The results of the respiratory muscle endurance tests did not reveal a significant difference in terms of load and time in all 3 conditions ( P > 0.05). Conclusion: After DOMS, there was a 4% to 7.5% decrease in respiratory function parameters, and a 6.6% decrease in respiratory muscle strength. Clinical Relevance: The occurrence of DOMS before a competition can have a detrimental impact on pulmonary performance. Hence, it is imperative to consider this factor when devising training and exercise programs. In addition, the development of treatment protocols becomes crucial if DOMS arises.

Predicting gas flow rate in fractured shale reservoirs using discrete fracture model and GA-BP neural network method

In the process of shale gas exploitation, the hydraulic fracturing technology is generally used to generate the stimulate reservoir volume (SRV). The network connectivity between natural fractures (NFs) and hydraulic fractures (HFs) significantly affects gas production rate in the hydraulic fracturing stage. To study the influence of natural fracture characteristics on gas flow behavior, a discrete fracture model considering matrix and fracture behaviors is developed. It is found that the increase of natural fracture permeability and distribution density leads to the increase of gas production rate, whereas large orientation angle may cause its decrease. To determine the nonlinear relationship between the natural fracture parameters and gas production rate, the method of back propagation (BP) neural network with genetic algorithm (GA) was applied to make intelligent prediction for the shale gas production. The gas flow rate values for different natural fracture parameters (e.g., permeability, density, orientation) were calculated by discrete fracture model, and used as input data for training and prediction in the GA-BP neural network. Results demonstrate the applicability of forecasting model, which is suitable for shale gas prediction during the operation of horizontal wells if more data profiles could be collected.

Influence of the centrifugal pump impeller vanes parameters on its energy performance at operating with high-viscosity liquid

BACKGROUND: The currently existing methods for recalculating the operation of centrifugal pumps for viscous fluids cover a sufficiently small range of viscosities. In addition, the considered papers cover the recalculation only, not the search for the optimal geometry of the centrifugal pump for high-viscosity liquids. In this paper, computational fluid dynamics tools were used to test the ability of centrifugal impellers to pump liquids with a viscosity of up to 20,000 sSt, as well as to search for the optimal geometry of the flow path.
 AIM: Determination the dependence pattern of the geometric parameters, including vanes, of the optimal geometry of the centrifugal pump flow path at various values of flow rate and viscosity.
 METHODS: A numerical modeling method based on the solving of discrete analogs of the basic equations of hydrodynamics is used in this paper.
 RESULTS: It was proved that, with the considered viscosities, an impeller with a profiled vane, but with a smaller wrap angle and height, is capable of more efficient operation than a disk impeller. The dependences of the parameters of the optimal flow paths on the characteristics for which their optimization was carried out are given.
 CONCLUSION: Based on the study results, it can be stated that it is advisable to use centrifugal impellers in case of high viscosity of the liquid, taking into account the choice of non-classical values of the geometric parameters of the flow path, including the height and angle of its vanes.

Thermal-Hydraulic comparative analysis of G-III + BWR and PWR passive safety features under Loss of coolant accident

As one of symbolic design features of Generation-III and III+ (G-III and G-III + ) nuclear reactors, the passive safety system has been implemented on majority of G-III and III + PWRs and BWRs. The passive safety systems in those reactors are designed differently yet adhere to identical fundamental principles. It would be interesting to examine the similarities and differences between the passive safety systems of G-III + PWR and BWR. System code simulations for Small Break and Large Break Loss of Coolant Accident for the Economic Simplified Boiling Water Reactor (ESBWR) and China’s advanced PWR had been conducted, respectively. The results showed that the passive safety systems of ESBWR and China’s Advanced PWR were comparable in design, and when dealing with the similar type of SBLOCA and LBLOCA, the passive safety components with the same functionality could all contribute to the core's cooling with stability and reliability, and the injection flow rate values were nearly equivalent. Separating the injection lines of ESBWR's safety systems guarantees that the action sequence could well remain stable. This design could prevent the injection flow rate and action sequence from being impacted by the interaction of safety injection systems. This work could serve as a reference for the design of subsequent new reactors, thereby contributing to the design of reactors with enhanced economics and safety.

Quantification of face seal leakage using parallel resistance model

Mask-wearing emerged as the key safety measure to prevent the spreading of COVID-19. In this study, we hypothesized a model to quantify the leakage flow rate through the face mask based on a parallel resistance model. The tests were performed in two ways: (I) mask material test, in which all masks were sealed to a flange to measure transmission through a full mask and prevent leakage around the edges, and (II) mannequin mask test, in which masks were fitted to a mannequin head tightly. For all masks, the pressure drop was measured at eight different flow rates between 5 and 85 LPM, and it was increased linearly with the flow rate (r2 > 0.98). The results of the study showed that the leakage flow rate was 10% of the total flow rate, even for the best-fitted N95 filtering facepiece respirators (FFRs) and KN95 masks. They showed higher resistance to the leaks. The procedure masks and cloth masks showed a leakage flow rate of 25% of the value of the total flow rate, quite a large proportion of the flow. They had lower resistance to leaks.

Effect of Changing the Water Flow Rate on the Efficiency of Hybrid PV/T Uncovered Collectors without Glasses: Numerical Study

The flat-plate collector is one of the most frequent types of collectors because it is simple to manufacture and it is relatively inexpensive in comparison to other collectors. The primary objective of this work is to improve the collector's efficiency, which can be accomplished by increasing the heat transfer quantitatively. This can be accomplished by increasing the efficiency of the collector. In this research employs hybrid photovoltaic panels through electrical generation and, on the other hand, takes advantage of the lost heat, which has reduced efficiency to useful heat, by transporting them through fluid and benefiting from them through industrial and domestic applications. The model was studied numerically by ANSYS computational code, where simulations were carried out on CFD and steady state thermal, as well as the effect of solar radiation, at a value of 10, on the layer of photovoltaic cells. Besides, several values of flow rate (0.02, 0.025, and 0.03) were used and compared. The current findings show that the efficiency of the current panel under consideration increased significantly, and the value of flow of 0.03 was the optimal value that led to obtaining suitable efficiency and a relatively acceptable water temperature.

Using hydrophone measurements to monitor incipient cavitation in variable displacement pendulum-slider pumps

The present work proposes an experimental methodology for monitoring the inception and the subsequent development of cavitation and aeration in variable displacement pendulum-slider pumps. These two phenomena may affect volumetric machines when the working condition requires high values of working speed and specific displacement, often causing undesired broadband noise. Since these pumps find their most common application in automotive auxiliary systems and powertrain lubricating circuits, the abnormal noise caused by this phenomenon is often unacceptable. Based on these considerations, an experimental cavitation detection method based on hydrophone measurements is proposed and assessed through direct comparison with a non-cavitating machine. Cavitation is promoted by increasing the pump working speed, as it happens in actual automotive applications. The effective presence of cavitation is further checked with the help of durability tests and efficiency measurements, made possible by the capability to control the pump working eccentricity. Measurements are repeated for different values of both specific flow rate and oil temperature, showing that these operational parameters have a consistent interaction in the definition of the inception of the phenomenon and its intensity.

Electro-rheological flow of seminal fluid (K-L MODEL) induced by movement of cilia in a circular conduit

The current study deals with the flow of seminal fluid through the ductus efferentes owing to electro-osmotic force and motion of cilia. The constitutive equation of semen liquid has been assumed to be described as a K-L (Kuang and Luo) fluid model. The main equations of the ciliary flow of K-L model are solved by considering the supremacy of viscous upshot over inertia influence assuming the state of long wave-length number. The analytic expressions for velocity profile, flow rate and flow impedance are derived. This is the first time to bring out to the lime light that the flow impedance is decreased and the plug core radius is enlarged with the introduction of electric force in the ciliary flow system. The effects of pertinent physiological parameters on the time-mean flow rates of rhesus monkey and human semen are thoroughly investigated. The computational mean flow rate's value over the period of time of the current mathematical model has been well matched with the corresponding experimentation values of the time-mean flow rates of rhesus monkey and humanoid semen in the path of generative and the vas deferens of the path of generative of male. Introduction of electric field into the flow ciliary system and the rheology of semen fluid described as K-L fluid model (for the values of rheological parameters of K-L fluid are considered) reduce the flow resistance, which in turn elevates the flow velocity of seminal fluid, which activates the significant and favorable changes for Oocytes getting fertilized within hours of ovulation by means of reasonable volume of semen transport into the female reproductive tract to partake a quick contact with cervical mucus and enter the cervix.

Numerical analysis of multipurpose shell-tube-heat exchanger withal stylized geometry at different baffle gaps and various flow rates

The effects of changing 90 mm and 110 mm plate spacings and FR factor of 0.9 kg/h, 1.3 kg/h, 1.7 kg/h, 1.9 kg/h on the total heat transfer performance and PD in the new design HX were examined. The results obtained by taking into account the change in plate spacing and FR factor of 0.9 kg/h, 1.3 kg/h, 1.7 kg/h and 1.9 kg/h, as well as variable factors, were transferred to the study and displayed in figures. In the study, firstly, the results of HCO obtained by changing FR and range were monitored. In the analysis, the interval values were 90 mm and 110 mm and the changes in the FR values of 0.9 kg/h, 1.3 kg/h, 1.7 kg/h and 1.9 kg/h increased in direct proportion. The smallest value of the heat transfer rate was obtained at 110 mm plate spacing and 0.9 kg/h FR. In addition, if the plate spacing was 90 mm, the smallest HCO was obtained at 0.9 kg/h. The largest HCO was obtained when the plate spacing was 90 mm and FR was 1.9 kg/h. In the second part of the study, the results of PD obtained by changing FR and gap were monitored. In the analysis, the interval values were 90 mm and 110 mm and the changes in FR values of 0.9 kg/h, 1.3 kg/h, 1.7 kg/h and 1.9 kg/h increased in direct proportion. The smallest value of PD level was obtained at 90 mm plate spacing and 0.9 kg/h FR. In addition, if the plate spacing was 110 mm, the smallest heat transfer coefficient was obtained at 0.9 kg/h. The largest PD value was obtained when the plate spacing was 110 mm and FR was 1.9 kg/h. In the last part of the study, the results obtained by changing FR and range of the HTPD value were monitored. In the analysis, the interval values were 90 mm and 110 mm, and the changes in FR values of 0.9 kg/h, 1.3 kg/h, 1.7 kg/h and 1.9 kg/h decreased in direct proportion. The smallest value of the HTPD level was obtained at 110 mm plate spacing and 1.9 kg/h FR. In addition, if the plate spacing was 90 mm, the smallest HTPD value was obtained at 1.9 kg/h. The highest HTPD value was obtained when the plate spacing was 90 mm and FR was 0.9 kg/h. Therefore, choosing a system with a 90 mm plate spacing and a FR of 0.9 kg/h will be more efficient in terms of thermohydraulic performance and pressure balancing. As a result, it was concluded that if the plate spacing was selected as 90 mm, a 15 % improvement could be achieved compared to the system design with a 110 mm plate spacing. As a new, it is thought that it will contribute to the literature in future studies, as the thermal performance, pressure drop and heat transfer coefficient results obtained at new flow rate values and compartment spacing values are obtained for the first time in a new STH designed in different dimensions than the literature.

Sampling from Extracorporeal Circuit: A Step Forward for Dose Monitoring in Continuous Renal Replacement Therapy

Introduction: Continuous renal replacement therapies (CRRTs) require constant monitoring and periodic treatment readjustments, being applied to highly complex patients, with rapidly changing clinical needs. To promote precision medicine in the field of renal replacement therapy and encourage dynamic prescription, the Acute Dialysis Quality Initiative (ADQI) recommends periodically measuring the solutes extracorporeal clearance with the aim of assessing the current treatment delivery and the gap from the therapeutic prescription (often intended as effluent dose). To perform this procedure, it is therefore necessary to obtain blood and effluent samples from the extracorporeal circuit to measure the concentrations of a target solute (usually represented by urea) in prefilter, postfilter, and effluent lines. However, samples must be collected simultaneously from the extracorporeal circuit ports, with the same suction flow at an unknown rate. Methods: The proposed study takes the first step toward identifying the technical factors that should be considered in determining the optimal suction rate to collect samples from the extracorporeal circuit to measure the extracorporeal clearance for a specific solute. Results: The results obtained identify the low suction rate (i.e., 1 mL/min) as an ideal parameter for an adequate sampling method. Low velocities do not perturb the external circulation system and ensure stability prevailing pressures in the circuit. Higher velocities can be performed only with blood flows above 120 mL/min preferably in conditions of appropriate filtration fraction. Discussion/Conclusions: The specific value of aspiration flow rate must be proportioned to the prescription of CRRT treatments set by the clinician.

Maximization of Power Density of Direct Methanol Fuel Cell for Greener Energy Generation Using Beetle Antennae Search Algorithm and Fuzzy Modeling.

Direct methanol fuel cells (DMFCs) are promising form of energy conversion technology that have the potential to take the role of lithium-ion batteries in portable electronics and electric cars. To increase the efficiency of DMFCs, many operating conditions ought to be optimized. Developing a reliable fuzzy model to simulate DMFCs is a major objective. To increase the power output of a DMFC, three process variables are considered: temperature, methanol concentration, and oxygen flow rate. First, a fuzzy model of the DMFC was developed using experimental data. The best operational circumstances to increase power density were then determined using the beetle antennae search (BAS) method. The RMSE values for the fuzzy DMFC model are 0.1982 and 1.5460 for the training and testing data. For training and testing, the coefficient of determination (R2) values were 0.9977 and 0.89, respectively. Thanks to fuzzy logic, the RMSE was reduced by 88% compared to ANOVA. It decreased from 7.29 (using ANOVA) to 0.8628 (using fuzzy). The fuzzy model's low RMSE and high R2 values show that the modeling phase was successful. In comparison with the measured data and RSM, the combination of fuzzy modeling and the BAS algorithm increased the power density of the DMFC by 8.88% and 7.5%, respectively, and 75 °C, 1.2 M, and 400 mL/min were the ideal values for temperature, methanol concentration, and oxygen flow rate, respectively.

Prognostic value of flow-status in severe aortic stenosis patients undergoing percutaneous intervention

PurposeLow-flow status is a mortality predictor in severe aortic stenosis (SAS) patients, including after transcatheter aortic valve implantation (TAVI) treatment. However, the best parameter to assess flow is unknown. Recent studies suggest that transaortic flow rate (FR) is superior to currently used stroke volume index (SVi) in defining low-flow states. Therefore, we aimed to evaluate the prognostic value of FR and SVi in patients undergoing TAVI.MethodsA single-centre retrospective analysis of all consecutive patients treated with TAVI for SAS between 2011 and 2019 was conducted. Low-FR was defined as < 200 mL/s and low-SVi as < 35 mL/m2. Primary endpoint was all-cause five-year mortality, analyzed using Kaplan-Meier curves and Cox regression models. Secondary endpoint was variation of NYHA functional class six months after procedure. Patients were further stratified according to ejection fraction (EF < 50%).ResultsOf 489 cases, 59.5% were low-FR, and 43.1% low-SVi. Low-flow patients had superior surgical risk, worse renal function, and had a higher prevalence of coronary artery disease. Low-FR was associated with mortality (hazard ratio 1.36, p = 0.041), but not after adjustment to EuroSCORE II. Normal-SVi was not associated with survival, despite a significative p-trend for its continuous value. No associations were found for flow-status and NYHA recovery. When stratifying according to preserved and reduced EF, both FR and SVi did not predict all-cause mortality.ConclusionIn patients with SAS undergoing TAVI, a low-FR state was associated with higher mortality, as well as SVi, but not at a 35 mL/m2 cut off.

Experimental study of the effect of load and rotational speed on the electrical power of a high-speed ORC microturbogenerator

The article presents the results of the study conducted on a microturbogenerator with a nominal power of 1 kWe. One of the primary objectives of the study was to determine the maximum power of the microturbogenerator for several preset and constant flow rates of the HFE-7100 working medium. During the tests, the variable parameters were the power of the heat source and the electrical load of the microturbine generator. Such a methodological approach made it possible to determine the experimental mechanical and electrical characteristics of the high-speed microturbogenerator, which are practically absent in the subject literature at present.The study shows that, at a preset working medium flow rate, there exists an optimum heat source power level at which the microturbogenerator's power output is maximum. It was determined that the maximum electrical power also depends on the load value of the microturbine generator. At the minimum tested working medium flow rate value of 30 g/s, a maximum power of approx. 210 We was obtained with a heat source power of 12 kWt and a resistive load of approx. 6.4 Ω. On the other hand, at the same flow rate value of the HFE-7100 and a heat source power of 14 kWt, the maximum electrical power of the microturbogenerator was approximately 205 W. On the other hand, for an HFE-7100 flow rate of 60 g/s, the maximum electrical power of approximately 625 W was achieved with a heat source power of 18 kWt. It was found that the load current of the generator had a major influence on the maximum electrical power of the microturbogenerator.

Chengai Nomogram: A Comprehensive Study of Uroflow Parameters and Characteristics in Healthy Adult Males From South India.

Introduction Uroflowmetry is a widely accepted non-invasive diagnostic modality used in the evaluation of lower urinary tract dysfunction. While various nomograms have been established for different populations and races, there has been a lack of studies that focus on the South Indian populations. Consequently, the objective of the study was to investigate the urinary flow parameters in a healthy adult male South Indian population using uroflowmetry and identify the variations in flow rates. Additionally, the study sought to assess the influence of age and voided volume (VV) on flow rates and create a representative nomogram. Methods A total of 500 uroflowmetry tests were prospectively performed on healthy adult males. The gravimetric method was utilized for uroflowmetry. Flow charts and parameters were analyzed for correlation and linear regression models, and statistical calculations were employed to generate uroflow nomograms. Results The mean age of the participants was 37.77±9.91 years. The mean values for maximum flow rate (Qmax), average flow rate (Qavg), and VV were 23.42±6.64 mL/s, 11.71±3.77 mL/s, and 229.90±59 mL, respectively. A significant correlation was observed between flow rates (Qmax and Qavg) and VV, which indicated that increased VV leads to higher flow rates. Additionally, a significant negative correlation between the flow rates and age was noted. Conclusion The findings provide insight into the uroflow parameters of the South Indian adult male population and contribute to the development of nomograms, establishing normal reference ranges for flow rates across varying VVs. As a tribute to the hospital and the study participants, the nomogram was named the "Chengai Nomogram."

Coronary Flow Reserve Changes after Angiotensin Receptor-Neprilysin Inhibitor Treatment in Heart Failure with Reduced Ejection Fraction.

Sacubitril/valsartan has been shown to reduce hospital admissions and even mortality for heart failure. In heart failure and acute coronary syndrome, the effects of sacubitril/valsartan have been studied, but the effect on coronary artery flow is not known. We aimed to understand the effect of sacubitril/valsartan on coronary artery flow by using echocardiographic coronary flow reserve (CFR). Thirty-six patients (17 ischemic and 19 non-ischemic) with heart failure with reduced ejection fraction (EF of < 40%) eligible for sacubitril/valsartan treatment and 21 normal controls were recruited. The study group and controls were similar with regard to gender, smoking status, and age distribution (p = 0.874, p = 0.709, and p = 0.765, respectively). Blood pressure, heart rate, 6-minute walk test (6MWT), N terminal pro B type natriuretic peptide (NT-pro-BNP) level, standard echocardiography, from where left anterior descending mid-distal flow was seen, baseline peak diastolic flow rate and 2 minutes after dipyridamole infusion, and hyperemic peak diastolic flow rate were measured, and CFR with echocardiography was assessed prior to and at 6 months after sacubitril/valsartan initiation. Baseline peak diastolic flow rate did not exhibit a significant difference at 6 months (p = 0.143), but hyperemic peak diastolic flow rate, CFR, EF (%), and 6MWD values were significantly increased (all p < 0.001), and New York Heart Association Functional Class, NT-pro-BNP (pg/mL), left ventricule end diastolic diameter (mm), and left ventricule end systolic diameter (mm) values were significantly decreased (all p < 0.001) after sacubitril/valsartan treatment. Sacubitril/valsartan significantly alters coronary blood flow, especially its dynamic features, in patients with heart failure with reduced ejection fraction.

A novel two-step optimization approach for film water cooling of a photovoltaic module in real ambient conditions

Efficiency of photovoltaic (PV) modules decreases as they get warmer in real working conditions. One way to address this issue is to apply water-film cooling on the front surface of a PV module. In order to circulate water over the surface of a module, a power-consuming pumping system is required. This paper presents a novel two-step optimization algorithm for improving the water-film cooling system to maximize the net energy generation of a photovoltaic (PV) panel. In the first step, the fluctuations of the optimal water flow rate during a specified day are calculated and then ideal water flow rates on daily and monthly basis are determined. Since the value of the optimum specific water flow rate is a nonlinear function of ambient conditions, it was calculated through an iterative algorithm. In the second step, the appropriate activation time interval for a water-cooling system was determined to furthermore maximize power gain and minimize energy consumption. By optimizing both water flow rate and cooling system timing, a significant improvement in net efficiency was achieved, increasing from 13.98%, 13.85%, and 13.87% in June, July, and August to 14.82%, 14.86%, and 14.80% in Shiraz, Iran.

Thermal response of an asphalt solar collector: Numerical and experimental validation

This study conducts a numerical analysis and experimental validation of the thermal performance of an asphalt solar collector. Both parallel and serpentine copper tubes with a total length of 3000 mm were embedded in the middle of a 1000 × 600 × 80 mm hot mix asphalt model. The sides and bottom of the test sections were insulated to prevent heat loss to the surrounding environment. Using four values of water mass flow rate and three values of artificial solar radiation, the thermal performance of the system was examined. A mass flow inlet of 0.0038–0.035 kg/s is specified for the water inside the embedded tubes, while 600, 800, and 1000 W/m2 solar radiation is applied on the upper section of the asphalt mix during this study. The thermal response was simulated using the COMSOL Multiphysics 5.6.0.280 heat transfer module. Using a reference asphalt solar collector, the desired parameter effects were investigated independently. The experimental results showed that the efficiencies of the asphalt solar collector with serpentine bare tubes and parallel bare tubes are 53.56 % and 52.85 %, respectively. The numerical simulation reveals that there is no significant thermal effect in the area under the embedded tubes when compared to the area above the tubes that are exposed to solar radiation from above. The average error found between the numerical and experimental results for the water temperature difference inside the embedded tubes of the asphalt solar collector ranged between 6 % and 14 %. This good agreement indicated that the computational fluid dynamics model is reliable and capable of simulating the thermal response of an asphalt solar collector.

Fast Calculation of Supercritical Carbon Dioxide Flow, Heat Transfer Performance, and Mass Flow Rate Matching Optimization of Printed Circuit Heat Exchangers Used as Recuperators

Printed circuit heat exchangers (PCHEs) are widely used as recuperators in the supercritical carbon dioxide (S-CO2) Brayton cycle design. The variation of heat sources will have a great impact on the heat transfer effect of the recuperator. It is of interest to study the fast calculation of flow and heat transfer performance of PCHEs under different operating conditions to obtain the optimal comprehensive performance and provide guidance for the operation control strategy analysis. Herein, a fast calculation method is established through a one-dimensional model of a PCHE based on Modelica. The effects of working medium mass flow rate and inlet temperature on the flow and heat transfer process are analyzed from the three aspects of heat transfer rate, flow pressure drop, and comprehensive performance, and the mass flow rate matching optimization is realized. The results show that increased mass flow rate increases heat transfer rate and flow pressure drop. The efficiency evaluation coefficient (EEC) has a maximum value at which the mass flow rate values of the cold and hot channels are best matched, and the comprehensive performance is optimal. When the mass flow rate of the heat channel is 4.8 g/s, the maximum EEC is 1.42, corresponding to the mass flow rate of the cold channel, 4.2 g/s. Compared with the design condition, the heat transfer rate increases by 62.1%, and the total pump power increases by 14.2%. When the cold channel inlet temperature increases, EEC decreases rapidly, whereas EEC increases when the hot channel inlet temperature increases. The conclusions can provide theoretical support for the design and operation of PCHEs.

Numerical simulation of thermo-throttle for iodine flow rate control in multidirectional plasma thruster

Background: Recently, a new direction in the field of electric propulsion has emerged – the multidirectional plasma thrusters. These thrusters are capable of producing propulsive forces in multiple directions. The thrusters are proposed to be used for orbit maintenance and alterations, formation flights, and interplanetary flights of space artificial objects ranging in size from CubeSats to fusion-powered interplanetary spacecraft. In this paper, the results of numerical simulation of the iodine propellant supply system for the multidirectional plasma thruster are presented. Methods: The geometry and temperature parameters of propellant supply system various elements are varied to determine the stable modes of iodine propellant ejection into the gas discharge chamber of the thruster. The temperatures of the thermo throttle and filter are found to ensure iodine mass flow rate in the range of 0.1 to 1.5 mg/s. The thermo throttle and filter temperatures are altered in the range of 65 to 200 °C and 65 to 100 °C, correspondingly. Results: The mass flow rate is critically dependent on the filter temperature and iodine saturated vapor pressure, as well as the filter and throttle geometries. The required values of iodine flow rate have been achieved by using the throttle with a diameter of 0.5 mm and a length of 60 mm and a filter with 56 holes, each hole diameter is 0.2 mm, and temperature from 90 C to 200 C. Conclusions: According to the data obtained, the iodine storage and supply system is preferably equipped with a thermos throttle, which provides precise control of the flow rate, as well as reduces sharp jumps of the flow rate when the temperature of the filter changes. Preferred filter geometry: 56 holes, each hole 0.2 mm in diameter.

Multi-effect Distillation with Heat Pump Integrated

This article presents a study and simulation of the desalination system consisting of a heat pump HP and a multi-effect distillation MED unit. Electric energy using in HP is provided by photovoltaic panels and wind turbines ,for a possible installation of the system on an isolated sites.The proposed desalination system uses an additional source of thermal energy in order to make HP and MED integration optimal and to reduce HP Electrical energy consumption per cubic meter of distilled water (kwh/m3).The main idea is to use geothermal-solar thermal energy and heat from HP as two thermal inputs in the multi-effect distillation unit MED. Thermal rejection from MED is recovered to be used as heat input in HP that based on mechanical compression of working fluid. The HP can use the working fluids (R22, ammonia) for a number of reasons, including that the two previous fluids are very dense at the saturated vapor state compared to water. A thermodynamic analysis of the desalination system was performed at steady state, using the thermodynamic properties of the Coolprop database. The simulation results showed a minimum value of electrical energy consumption, without consideration the contribution of auxiliary thermal energy :(10.487 kwh/m3 | effect numbre:5).The simulation results showed a minimum value of volumetric flow rate of the working fluid ,before compression : (17.685 m3 of working fluid per m3 of distilled water | effect numbre:12 | contribution ratio of auxiliary thermal energy:46.6 %).